1. Field of the Invention
The present invention relates to engines and more specifically to an improved internal combustion engine having an open thermodynamic cycle where air and fuel expand to move a piston, perform work and vent exhaust to the environment and a closed loop thermodynamic cycle that converts wasted heat from the open cycle into electrical and chemical energy.
2. Introduction
In a typical diesel engine, such as one used for large vehicles such as semi-trucks, an open thermodynamic cycle receives a mixture of diesel fuel and air, compresses and combusts the mixture to drive pistons in the engine. The moving pistons produce mechanical work in the form of a turning drive shaft. The output of the thermodynamic process is mechanical work plus waste products such as heat and exhaust that are emitted into the surrounding atmosphere. Since the output is emitted into the surroundings, the cycle is referred to as an “open loop.” The efficiency of such an engine is typically around 45% and much energy is lost in the form of waste products.
Attempts have been made to utilize the energy available from the heat and exhaust. For example, U.S. Pat. No. 3,939,806 to Bradley (“Bradley”) discloses a closed circulatory system that generates energy from the exhaust heat of an engine. FIG. 1 generally illustrates the engine 10 and closed loop cycle 20 of Bradley. The same numbering scheme from Bradley's FIG. 1 is preserved.
In Bradley, heat from the exhaust 18 is transferred to a cool working fluid 27 which operates in a closed-loop cycle 20, which drives a turbine 24 to produce current to a generator 31. DC current is delivered to an electrolysis cell 32 that produces oxygen 34 and hydrogen 33 by decomposing water. The oxygen 53 is passed to an air intake on the engine 10 and the hydrogen may also be passed 51 to the engine. The working fluid 21 is condensed in condenser 26 to complete the closed loop 20.
In general, Bradley's device 100 has a number of deficiencies. For example, a turbine 24 will typically operate in a very narrow range of performance. Vehicles travel down the road at many variant revolutions per minute, under different loads and at many different speeds. With these variables, the engine cannot produce the narrow range of outputs needed by a typical turbine. Such a turbine does not function efficiently because it is unable to adjust to these described variations based on the loads and other factors. Because of these limitations on the operation of turbines, a deficiency in this system and on its performance exists.
Bradley also notes that their system is in communication with the cooling system of the engine block 10. However, Bradley ignores other heat generated by the engine 10. Because the Bradley concept fails to take into account other sources of heat beyond the existing cooling system 22, it is therefore further flawed. Outputs of hydrogen and oxygen are limited by the amount of electricity the system can generate because other heat sources are ignored. In relative terms, the Bradley device delivers very small quantities of hydrogen and oxygen from electrolysis to the engine intake and combines them with ambient air without reforming the fuel prior to ignition. Optimal increase in combustion and decrease in emissions is not achieved.
Another deficiency in the Bradley system is the lack of sufficient radiator surfaces to cool the closed loop system. The working fluid in a closed system needs to be cooled properly. Bradley does show a condenser 26 to convert the gaseous form of the working fluid into a liquid again, but there is not a sufficient disclosure with regards to mechanisms for being able to recycle the working fluid in the second closed loop system.
Government established exhaust emission standards require manufacturers to design environmentally-friendly engines. Due to current deficiencies in the art, engines that meet the cleaner air standards can only be achieved at the expense of engine efficiency/fuel economy. This is a significant problem given the fact that fuel prices continue to increase, not only because known oil reserves are being depleted, but because global consumption is sharply rising. The need for more fuel-efficient vehicles continues to grow.
There are theoretical limits to the energy that may be generated from an engine and increasing the efficiency of an engine by even a few percentage points is difficult. Accordingly, what is needed in the art is an improved engine that utilizes the waste heat more efficiently to increase the amount of mechanical work derived from fuels. Further, what is needed in the art is a way to enable vehicle manufacturers to meet government emissions standards while simultaneously increasing fuel economy.